An arrangement is known from U.S. Pat. No. 4,504,982, which describes a correction of a signal, which is used as a fuel metering signal for operating an internal combustion engine. The object is, for example, the attainment of a pregiven air/fuel ratio (lambda) in order, on the one hand, to obtain the least possible consumption of fuel and, on the other hand, to obtain an exhaust-gas composition which can substantially be freed of poisonous constituents. Different corrective quantities are provided which are directed to the compensation of different faults.
One such fault is, for example, a defective measurement of an air-mass sensor which operates multiplicatively on the fuel metering. Another fault is, for example, leakage-air influences which operate additively on the fuel metering. Furthermore, faults can occur in the utilized fuel injection valves which are especially caused by switch delays. These faults likewise operate additively. Such systematic faults are corrected by the corrective quantities in their effect.
The faults operate differently in different load ranges/rpm ranges of the internal combustion engine. Additive faults preferably occur in the lower load/rpm range and multiplicative faults occur especially in the mid load/rpm range.
In accordance with statutory regulations, exhaust-gas relevant faults are to be detected and displayed with on-board means. The correction can assume this task. If, for example, the corrective intervention lies above or below a permissible threshold, then this indicates a fault. In order to ensure an optimal cooperative relationship of the various engine control and diagnostic functions, the correction is enabled phase-wise by means of a time and/or event control.
U.S. Pat. No. 6,394,063 discloses a program for controlling an internal combustion engine wherein the switchover between a stratified operation and a homogeneous operation is provided in a direct-injecting internal combustion engine.
In stratified operation, the engine is operated with a stratified cylinder charge and high air excess in order to achieve the lowest possible fuel consumption. In contrast, at higher load the engine is operated with a homogeneous cylinder charge in order to make available the highest possible power. The correction for the signal is based on an actuating variable which is determined from the signal of a lambda probe. For this reason, a proper lambda probe control signal must be present at least during the correction. In the fuel-saving stratified operation of the direct-injecting engine for which a high air excess occurs, the signal of the lambda probe is, however, not always reliable because of the high air excess. The correction therefore takes place in a practical manner only during homogeneous operation. In the event that a corrective phase is provided and the internal combustion engine is in stratified operation at this time, a switchover into the homogeneous operation takes place at the start of the correction. With a view to the optimization of the fuel consumption, a time duration of the correction as short as possible is strived for.
Additional target conflicts with other control functions can result during the time duration of the correction. One such function is, for example, tank venting which has an influence on the signal to be corrected and therefore cannot be activated during the time duration of the correction. The time duration of the correction should be optimized also for such reasons.